Suture anchors used to secure sutures in openings formed in bones are important for joint reconstructive surgery and arthroscopic surgical techniques. Such suture anchors are used, for instance, to anchor ligaments or tendons to bones in knee, shoulder and elbow reconstruction and repair operations.
Important attributes of bone anchors are that they be easy to insert, and provide a firm anchor. Bone anchors also should be simple and reliable. Bone anchors may be bio-absorbable or nonbio-absorbable depending upon the material used to form the bone anchor. Either can be used depending on the type of operation and selection of the surgeon.
Initially, one type of bone anchor took the form of a fish hook-type barb which was inserted into a hole and hooked into the soft marrow of the bone. Another prior approach to suture anchors is disclosed in Goble et al. U.S. Pat. No. 4,738,255. This patent discloses a suture anchor delivery system which uses a specialized two-piece anchor including an anchor rivet and a slotted ring. The anchor rivet is drawn into the slotted ring to deform the slotted ring into an acorn-shape when pressure is applied by an anchor mandrel through which the suture is drawn. This slotted ring includes slots that are split to allow the ring to be deformed and an anchor ridge is formed around the inside circumference of the slotted ring. As compared with the present invention, the Goble suture anchor is more complex in configuration and requires a specialized anchor delivery system for manipulating the two-piece rivet and slotted ring. Also, manufacture of the Goble suture anchor requires close tolerance assembly of the two-piece anchor and cooperation between the two parts of the anchor.
Another patent disclosing a system for fastening articles to bones is disclosed in Rosenberg U.S. Pat. No. 4,013,071. This patent discloses an orthopedic screw with an expandable portion including side slits which are formed radially through the distal end of a screw. The side slits produce a plurality of outwardly expansible tips that are flared by driving a rod-shape member through an internal bore of the orthopedic screw. The Rosenberg device is turned in a manner of a screw for insertion which presents some difficulties in performing arthroscopic procedures. Further, the Rosenberg device requires close tolerance in manufacturing and assembly.
Still another prior art system is shown in Hayhurst U.S. Pat. No. 4,741,330. This patent discloses anchoring devices for attaching sutures to bones, the anchoring devices being deformable cylindrical shaped solid plugs attached at their midpoints to sutures.
A primary objective of the present invention is to provide a bone anchor which is inexpensive to manufacture and simple to install.
Another object of the invention is to provide a bone anchor which automatically locks itself into a bore formed in a bone by simply applying pressure to the suture which causes the barbs or ridges in the bone anchor to dig into the walls of the hole in the bone locking the anchor to the bore hole.
Still another aspect of the present invention is to provide a bone anchor which is compact and automatically guides itself into the hole in the bone.
Another important object of the invention is to provide a bone anchor which may be formed by a simple molding operation with no close tolerance assembly operations required. This feature makes the bone anchor both economical and reliable.
A further object of the invention is to provide an inserter device for installing the bone anchor in place, as well as a spreader device for helping to firmly seat the anchor in the bone.
These and other objects are met by the present invention which will become apparent upon review of the following detailed description of the invention in view of the drawings.